FEVER

DEFINITION OF FEVER

Fever is an elevation of body temperature that exceeds the normal daily variation, in conjunction with an increase in hypothalamic set point

NORMAL BODY TEMPERATURE

Maximum normal oral temperature
At 6 AM : 37.2
At 4 PM : 37.7


Temperature ClassificationHypothermia<35.0 °C Normal36.5–37.5 °C Fever>37.5–38.3 °C Hyperthermia>37.5–38.3 °C Hyperpyrexia>40.0–41.5 °C Note: The difference between fever and hyperthermia is the mechanism

PATHOGENESIS OF FEVER

Infection
Tissue injury - infarction, trauma
Malignancy
Drugs
Immune-mediated disorders
Other inflammatory disorders
Endocrine disorders
Factitious of self-induced fever
CAUSES OF FEVER

without localizing signs or symptoms

Viral Rhinovirus, adenovirus, parainfluenza
Enterovirus Influenza

Bacterial Staphylococcus aureus
Salmonella thyphi, S. parathyphi
Streptococci
Post animal exposure
Coxiella burneti (Q fever)
Leptospira interrogans
Brucella species

Granulomatous infection Mycobacterium tuberculosis
Histoplasma capsulatum
Infections presenting as fever

Viral Measles,Rubella

Bacterial Brucellosis,Tuberculosis,Syphilis
(regional)
Pyogenic infection Sta. aureus, Stre.
Tuberculosis Scrofula (tbc. Cervical adenitis)
Inguinal lymphadenopathy Syphilis, herpes
Plague Yersinia pestis

Infections with Fever and Lymphadenomegaly (generalized)

DISCOMFORT DUE TO FEVER

HYPERTHERMIA

Heat production exceeds heat loss, and the temperature exceeds the individuals set point. Heat stroke ,drugs

TREATMENT OF FEVER

Most fevers are associated with self-limited infections, most commonly of viral origin.
Treatment of underlying cause

Treatment Strategies

Acetaminophen is generally a first-line antipyretic due to being well tolerated with minimal side effects.
Pediatric dose: 10-15mg/kg q4-6h (2400mg/day); adult: 650mg q 4 h(4000mg)
Can be hepatotoxic in high doses; can upset stomach

Clinical Pearls

Don’t give aspirin to children under 18 years (Reye’s Syndrome)Try water sponge bath; remove blankets and heavy clothing; keep room at comfortable temp

DRUG FEVER

PATHOGENEGIS
Contamination of the drug with a pyrogen or microorganism
Pharmacologic action of the drug itself
Allergic (hypersensitivity) reaction to the drug

DRUG FEVER

Onset and duration:
Onset: 1-3 weeks after the start of therapy
Duration: remits 2-3 days after therapy is stoped

DRUG FEVER

Fever out of proportion to clinical picture
Associated findings:
Rigor (43%), Myalgia (25%), Rash (18%), Headache (18%),
Leukocytosis (22%), Eosinophilia (22%), Serum sickness,Proteinuria Abnormal liver function test

APPROACH TO THE PATIENT WITH FEVER

ACUTE FEBRILE ILLNESS

APPROACH TO FEVER

Personal History:
Age
Occupation
Place of origin,Travel History
Habits
Sexual Practices
Injection Drug Abuse
Excessive Alcohol Use
Consumption of Unpasteurized Dairy Products

APPROACH TO FEVER

Underlying Diseases:
Splenectomy
Surgical Implantation of Prosthesis
Immunodeficiency
Chronic Diseases:
Cirrhosis
Chronic Heart Diseases
Chronic Lung Diseases

APPROACH TO FEVER

Drug History:
Antipyretics
Immunosuppressants
Antibiotics
Family History:
TB in the Family
Recent Infection in the Family

APPROACH TO FEVER

Associated Symptoms:
Shaking chills
Ear pain,Ear drainage,Hearing loss
Visual and Eye Symptoms
Sore Throat
Chest and Pulmonary Symptoms
Abdominal Symptoms
Back pain, Joint or Skeletal pain

APPROACH TO FEVER

Physical Examination:
Vital Signs
Neurological Exam.
Skin Lesions,Mucous Membrane
Eyes
ENT
Lymphadenopathy
Lungs and Heart
Abdominal Region (Hepatomegaly,Splenomegaly)
Musculoskeletal

LABORATORY STUDY IN PATIENT WITH FEBRILE ILLNESS

Assess the extent and severity of the inflammatory response to infection
Determine the site(s) and complications of organ involvement by the process
Determine the etiology of the infectious disease


FUO
FEVER OF UNKNOWN ORIGIN


FUO
Classic FUO
Nosocomial FUO
Neutropenic FUO
HIV-Associated FUO

Classic FUO

Definition:
Fever of 38.3 C or higher on several occasions
Fever of more than 3 weeks duration
Diagnosis uncertain, despite appropriate investigations after at least 3 outpatient visits or at least 3 days in hospital

Nosocomial FUO

Definition:
Fever of 38.3 or higher on several occasions
Infection was not manifest or incubating on admission
Failure to reach a diagnosis despite 3 days of appropriate investigation in hospitalized patient

Neutropenic FUO

Definition:
Fever of 38.3 or higher on several occasions
Neutrophil count is <500/mm3 or is expected to fall to that level in 1 to 2 days
Failure to reach a diagnosis despite 3 days of appropriate investigation

HIV-Associated FUO

Definition:
Fever of 38.3 or higher on several occasions
Fever of more than 3 weeks for outpatients or more than 3 days for hospitalized patients with HIV infection
Failure to reach a diagnosis despite 3days of appropriate investigation

Causes of classical FUO

Infections
22-58%
Neoplasms
up to 30%
Noninfectiouse inflammatory diseases
up to 25%
Miscellaneous causes
up to 25%
Undiagnosed
up to 30%

Infections commonly associated with FUO

Localized pyogenic infectionsIntravascular infectionsSystemic bacterial infections (Tuberculosis, Brucellosis,…)Fungal infectionsViral infectionsParasitic infections

Malignancies commonly associated with FUO

Hodgkin’s diseaseNon-hodgkin’s lymphomaLeukemiaRenal cell carcinomaHepatomaColon carcinomaAtrial myxoma

Noninfectious inflammatory diseases with FUO

Collagen vascular/ hypersensitivity diseasesLupusStill’s diseaseTemporal arteritis (Giant cell arteritis) Granulomatouse diseasesCrohn’s diseaseSarcoidosisIdiopathic granulomatouse disease

Miscellaneous causes of FUO

Drug fever
Factitious fever
FMF
Recurrent pulmonary emboli
Subacute thyroiditis

FACTITIOUS FEVER

Diagnosis should be considered in any FUO, especially in:
Young women
Persons with medical training
If the patients clinically well
Disparity between temperature and pulse
Absence of the normal diurnal pattern

Causes of FUO lasting > 6 month

Undiagnosed
19%
Miscellaneous
13%
Factitious
9%
Granulomatouse hepatitis
8%
Neoplasm
7%
Infection
6%
No fever
27%

Approach to FUO

Determine whether the patient has a true FUO
Workup of true FUO:
Careful history
Serial follow-up histories
Careful physical examination
Physical examination should be repeated

Laboratory examination:

CBC(diff)
PBS
ESR
U/A
S/E
Culture of blood, urine,…Skin testSerologyANA

Imaging:

CXR
Ultrasonography
Radiographic contrast study
Radioneuclide scan
CT or MRI

Invasive Procedures

Biopsies:
Bone marrow
Skin lesion
Lymph node
Liver
Temporal artery